Battle
by onesieandacalendar
Summary: Richard sends Addison, Mark and Derek to Vegas for a “conference.” Basically it’s the three of them, their insanely messed up lives and what the affair did to their friendship. Will be Mark/Addison mainly, with Derek/Addison undertones.
1. Chapter 1

**Thanks to McMuffin for beta-ing! :)**

**Disclaimer- _If_ I owned, this would've happened.**

* * *

Addison stands up from her seat, "This is completely unnecessary Richard."

Derek's head shoots up from the table. "I agree with Addison."

Addison turns to look at him confused, "Really?"

"I don't want to spend a week in the same hotel as you, probably the same floor, and I don't even want to think about this one but... possibly even the same room. So yes, really."

"Funny, Derek."

"Children, let the man speak."

"Shove it, Mark."

Mark grins.

Addison's face turns red, "No, no. I did not mean it like _that._"

"You did last night."

"MARK!"

Richard shuts his eyes in disgust, "I think that's enough Dr. Sloan. Honestly I'm surprised you guys aren't thrilled about this."

"Why on earth would we be thrilled about this?" Addison practically screams.

"It's _Vegas._"

"But it's Vegas with _them_." Addison looks at Derek and Mark, receiving a wink from Mark and a glare from Derek.

"Need I remind you that you three used to be best friends?"

Derek laughs, "Used to."

"Laugh all you want, you know it was really all _your_ fault."

"Really, Mark, do you seriously want to go there?"

"You'll leave tomorrow." And with that Richard walks out of the room.

* * *

"Wow." Addison says as she approaches the others, "light packers."

Mark coughs, "High maintenance."

"Fuck off."

"Oh, Addison's using her colorful vocabulary today."

"I'm not in the mood."

"You better get in the mood."

"What?"

Mark waves his plane ticket in front of her, "Guess who's sitting next to you on the plane?"

"Kill me."

* * *

"You know, we_ could_ make this plane ride very interesting."

"Oh really?"

"There's a bathroom."

"Dream on, Mark."

"I will."

* * *

"Hey buddy."

"You are not, in any way what so ever, my buddy."

"Love you too, Derek!"

"You know, he's never going to forgive you."

Mark turns to face Addison, "I know."

"Doctor Sloan, Doctor Shepherd, Doctor Montgomery?"

"Yes?"

"I'm Eric, and I'll be showing you your room."

Derek screams, "Room?"

"Yes, room."

"As in only one?"

"Who's the brain surgeon here?"

"Fuck off, Addison."

"Wow, see what eleven years of marriage does to you."

"No, see what _cheating on your husband with his best friend _does to you?"

"You were never there, Derek. You have no right."

"Stay out of it, Mark." Derek and Addison both say at the same time.

Eric clears his throat. Addison bites her lip, "Sorry."

"You'll be on the twenty-third floor, room 2317." Eric tells them as the step into the elevator, "And here are your keys."

"Thank you."

Once the elevator gets to the twenty-third floor and the three of them step out Eric continues, "Oh and Richard wanted me to let you know that there actually is no conference and he just did this so you could sort out your obvious… issues. Good day now." He finishes right before the doors close, bringing him back down to the lobby.

"You've got to be kidding me."

"I doubt he's kidding you, Addison."

"Derek I swear to god if you don't shut up I'll--"

"You'll what? Cheat on me?"

Addison stops, "_This_ Ends now, okay? I can't stay here for a week if you two are going to constantly be giving me this shit. So please, can this just _end?_"

"No."

"No."

"Perfect."

* * *

"Oh my god!" Addison screams when she opens the door to their suite, "It's _huge_."

"And happy Addison appears."

Addison smiles, "Richard is god."

"That's not what you said last--"

"Mark." Derek and Addison both warn.

"Fine, whatever."

"You two are seriously still sleeping together?"

"No." Addison says harshly.

"Okay."

"Shit!" Addison yells from the other room.

"What?"

"There are only two beds, and no couch."

Mark grins, "No. No there is no way I'm sleeping in the same bed as you."

"Oh come on."

"No."

"Why?"

"Because you have no idea how to keep your hands to yourself."

"Has that ever been a problem before?"

"No…Damnit."

Derek looks away, "I'm pretty sure this is the weirdest experience of my life."

"Agreed."

Silence.

Addison's eyes grow big.

"What? What is it?"

"I bet the room gets charged right to Richard's credit card."

"And?"

"And there's near an unlimited supply of alcohol on those shelves over there."

"And suddenly this trip is improving."

* * *

"It's three a.m. Go to sleep, Addison."

"I can't."

"You_ never_ can."

"It's gotten worse, lately."

Mark turns to face her, "I'm sorry."

"I'm an idiot."

"No, I am."

"No."

"Yes."

"No."

"Yes."

And when somewhat sane/sober Addison reappears she says, "I miss this."

Mark smiles, "Yeah, me too."

* * *

**Reviews make me update faster, FYI.**


	2. Chapter 2

**Thanks to everyone who reviewed!**

**And to McMuffin for beta-ing this.**

**Disclaimer- still don't own..**

**xxxxxxx**

"I have a question." Mark states while pouring himself a glass of _very _expensive orange juice the next morning.

Derek looks up from the TV, "Which is?"

"Why haven't we gone down to the casino yet?"

"Why haven't I gone down to the spa yet?" Addison asks as she enters the room post shower in nothing but a very short towel. Mark shoots Derek a look and then they both turn to face her. "What? You've both seen me in a lot less many times."

"But this is _now._"

"And I'm sorry, Derek but if you have a problem with looking a half naked woman, that's not my concern."

"That's not what I meant." Derek replies bitterly.

"I know but your reaction certainly brightened up my morning."

Mark stares across the counter at Addison, "What?"

"How are you not hung over?"

Derek laughs, "Addison can hold her alcohol better than anyone. It's actually kind of scary."

"But she--"

"Drank an entire shelf full of alcohol, I know."

"And now Addison is cheerful, and wants to go lay out by the pool."

"Addison is also talking in third person."

"Addison thinks Mark should leave her the fuck alone."

"I don't know, Mark, the pool kind of sounds like a good idea."

"What are you, a chick?"

"No…"

"What are you talking about...? OH!"

Addison rolls her eyes, "Yes there will be hot girls in bikinis, now let's go."

"You're in a towel."

"Right, be right back."

**xxxxxxx**

"It's like one hundred and ten degrees out here."

"Literally."

"I want to go back inside." Mark whines, "There are _no_ hot girls."

Addison coughs.

"Except you, of course."

"Better."

"What time is it?" Derek asks, attempting to see all the way across the pool to the clock on the wall but failing.

Addison reaches down and checks her phone, "Eleven thirty."

"I'm hungry."

"Let's eat."

"_Where_?"

"Room service?"

"Deal."

**xxxxxxx**

Addison walks into the kitchen/living room area of the suite holding up two dresses. "Should I wear the red one to dinner, or the black one?"

"The red one."

"You're only saying that because it's shorter and lower cut."

"And?"

Addison turns her head, "Derek, what about you?"

"The red one, but only because I think you'd look beautiful in it." Derek says, half sarcastically and half sincerely.

"See now he has the right idea, you we need to work on." Addison tells Mark before leaving the room to get dressed.

Mark turns to Derek, "What?"

"You just told your ex wife she'd look _beautiful_ in a red, sparkly dress."

"To be fair, I didn't say the sparkly part."

"Whatever."

**xxxxxxx**

"I'm ready."

"Thank god. It's only been what?" Mark turns to look at the clock, "Two and a half hours."

Addison walks into the room.

"And somehow I just forgot I was angry about the time." Mark says in awe.

"Whatever, let's just go."

Derek hands Addison her purse and Mark puts a hand on her back, guiding her out of the hotel room.

Maybe the next five days wouldn't be so bad after all.

**xxxxxxx**

"Name please?"

"Mark Sloan."

"Okay, Mr. and Mrs. Sloan and..."

"Derek Shepherd."

"And Derek Shepherd, this way please."

"Oh we're not, we're not married."

"My apologies, Miss."

Once they sit down Addison says, "I can't believe he thought we were married."

"You look like your married."

"How?"

Derek gestures down to the fact that their hands are intertwined. Addison's face turns red at the realization of it and drops her hand from his immediately. "Sorry."

"Are we getting wine?" The waiter asks as he approaches the table.

"Yes." All three of them answer together.

"Okay, glass or bott-"

"Bottle." Once again, all three of them answer.

"Alright then."

"Can you believe this?" Addison asks, after a moment of silence.

"Believe what?"

"This. That we're all here, together."

"I keep thinking it's a horrible nightmare I can't wake up from." Derek says, bluntly.

"No one's tried to kill anyone yet, that's good."

"It's only the second day."

"True."

"Do you remember the last time we went to Vegas?"

Mark laughs, "How could I forget? You and Derek kept me up all night. That is the last time I'm getting a room next to a couple unless I'm sure the walls are soundproof."

Addison blushes, "We were crazy back then."

"Yeah I remember you snuck into the O.R. to have sex and I had to guard the door for you. Then the chief came and asked me what I was doing alone in the hallway--"

"And you said you really needed some time to be _alone_ and all the on-call rooms were occupied." Derek says laughing, "I remember."

"He never looked at me the same again."

"I bet."

Silence.

"What happened to us?"

"We became us."

"That makes no sense."

Addison shakes her head, "It makes perfect sense."

**xxxxxxx**

"Let's watch a movie."

"Fine but Addison's not allowed to pick."

"Hey…"

"Let's watch _the ring_!" Mark says, grinning.

"Scary." Addison says backing up closer to Mark's lap.

"Okay."

Mark orders the movie and then takes his place back on the chair. Within twenty minutes, Addison is in his lap and hiding her head in his chest.

"It's not that bad, Addie."

"Are you kidding me?" Addison screams.

"Fine."

At the end of the movie Mark whispers, "Addie, it's over."

"I think she's asleep." Derek tells him.

"Yeah, she is."

"Want me to help you move her?"

"No it's fine, I'll stay here."

"You sure?"

"Yeah."

"Alright, good night Mark."

"Night, Derek."

**xxxxxxx**

**Reviews are lovely.**


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